let calculator = {
  read(){
    this.x = parseFloat(prompt("First Number:"));
    this.y = parseFloat(prompt("Second Number:"));
  },
  sum(){
    return this.x + this.y;
  },
  mul(){
    return this.x * this.y;
  }
};

calculator.read();
alert( calculator.sum() );
alert( calculator.mul() );
